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Modern Physics, , photo electric effect, , between nr and nv., Single choice questions, 1. We can say that the energy of a photon of frequency v 3. Light of wavelength  falls on a metal having work, is given by E = hv, where h is Planck’s constant. The, function hc/o. Photoelectric effect will take place only, momentum of a photo is p = h/, where  is the, if, wavelength of photon, then we may conclude that, , (a)   o (b)   2o, (c)o, (d)< o, velocity of light is equal to, 2, (a) (E/p)1/2 (b) E/p, (c) Ep, (d) (E/p)², 4. If the frequency of light in a photoelectric experiment is, 2. Let nr and nb be respectively the number of photons, doubled, the stopping potential will, emitted by a red bulb and a blue bulb of equal power in, (a) be doubled, (b) be halved, a given time, (c) become more than double, (a) nr = nb, (b) nr < nb, (c) nr > nb, (d) become less than double, (d) the information is insufficient to get a relation

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current, , 5. A point source of light is used in a photoelectric effect. If, the source is removed farther from the emitting metal,, the stopping potential, (a) will increase, (b) will decrease, (c) will remains constant, (d) will either increase or decrease, 6. A point source causes, a, photoelectric effect, from, b, a small metal plate., c, Which, of, the, following curves may, d, represent the, distance, saturation, photocurrent as a, function of the distance between the source and the, metal?, 7. A non-monochromatic light is used in an experiment on, photoelectric effect. The stopping potential, (a) is related to the mean wavelength, (b) is related to the longest wavelength, (c) is related to the shortest wavelength, (d) is not related to the wavelength, 8. Photoelectrons emitted from a metallic surface are those, which are, (a) present inside the nucleus, (b) orbiting very near to nucleus, (c) generated by the decay of neutrons within the, nucleus, (d) Free to move within inter atomic spacing., 9. Photoelectric effect can be explained by assuming that, light, (a) is a form of transverse waves, (b) is a form of longitudinal waves, (c) can be polarized, (d) consist of quanta., 10. Ultra-violet radiation of 6.2 eV falls on a aluminimum, surface (work function 4.2 eV). The kinetic energy (in, Joule) of the fastest electron emitted is approximately:, (a) 2x1021 (b) 3x1019 (c) 3x1017 (d) 3x1015, 11.The photoelectric threshold of the photo effect for a, certain metal is 2750 Å. The minimum energy of a, photon producing the photo effect is, (a) 0.45 eV, (b) 4.5 eV, (c) 0.045 eV, (d) 0.0045 eV, 12. Light of frequency 1.5 times the threshold frequency is, incident on photo-sensitive material. If the frequency is, halved and intensity is doubled, the photo current, becomes:, (a) quadrupled (b) doubled (c) halved (d) zero, 13.A photon of energy hv is absorbed by a free electron, function W < hv, (a) the electron is sure to come out, (b) the electron is sure to come out with a kinetic, energy hv-W, (c) either the electron does not come out or it comes, out with a kinetic energy hv-W, (d) it may come out with a kinetic energy less than hvW., 14. A surface ejects electrons when hitted by green light but, none when hitted by yellow light. Will electrons be, ejected if the surface is hitted by red light?, (a) Yes, (b) No, (c) Yes, if the red beam is quite intense, , (d) Yes, if the red beam continues to fall upon the, surface for a long time., 15. The maximum energy of emitted photoelectrons is, measured by, (a) the largest potential difference they can traverse, (b) the current they produce, (c) the potential difference they produce, (d) the speed with which they emerge, 16. A particle of mass M at rest decays into two particles of, masses m1 and m2 having non-zero velocities. The ratio, of the de-Broglie wavelengths of the particles 1/2 is ., (a) m1/m2 (b) m2/m1, (c) 1.0 (d) √(m2 )/√(m1 ), 17. Which of the following is a correct statement:, (a) Beta rays are same as cathode rays, (b) Gamma rays are high energy neutrons, (c) Alpha particles are singly ionized helium atoms, (d) Protons and neutrons have exactly the same mass., 18. A beam of electron is used in an YDSE experiment. The, slit width is d. When the velocity of electron is, increased, then:, (a) no interference is observed, (b) fringe width increases (c) fringe width decreases, (d) fringe width remains same, 19. Sodium and copper have work functions 2.3 eV and 4.5, eV respectively. Ten the ratio of the wavelengths is, nearest to, (a) 1 : 2, (b) 4 : 1, (c) 2 : 1, (d) 1 : 4, 20. A radiation of energy E falls normally on a perfectly, reflecting surface. The momentum transferred to the, surface is, (a) Ec, (b) 2E/c, (c) E/c, (d) E/c2, 21. A photocell is illuminated by a small bright source, placed 1 m away. When the same source of light is, placed 1/2 m away , the number of electrons emitted, by photocathode would, (a) increased by a factor of 4, (b) decrease by a factor of 4, (c) increase by a factor of 2, (d) decrease by a factor of 2, 22. If the kinetic energy of a free electron doubles, it’s, deBroglie wavelength changes by a factor, (a) 2, , (b), , 1, 2, , (c), , 2, , (d), , 1, 2, , 23. The anode voltage of a photocell is kept fixed. The, wavelength λ of the light falling on the cathode is, gradually changed. The plate current I of the photocell, varies as follows:, , I, , I, , (a), , (b), O, , λ, , O, , I, , I, , (c), , (d), O, , λ, , λ, , O, , λ

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24 The surface of a metal is illuminated with the light of, 400 nm. The kinetic energy of the ejected, photoelectrons was found to be 1.68 eV. The work, function of the metal is:, (a) 1.41 eV (b) 1.51 eV (c) 1.68 eV (d) 3.09 eV, 25. Photon of frequency v has a momentum, associated with it. If c is the velocity of light , the, momentum is, (a) h v/c, (b) v/c, (c) hvc, (d) h v/c2, 26. The work function of a substance is 4.0 eV. Then, longest wavelength of light that can cause, photoelectron emission from this substance, approximately, (a) 310 nm (b) 400 nm (c) 540 nm (d) 220 nm, , Vo, , A, , Vo, , C, , B, , B, , C, , A, , (c), , (d), v, , O, , v, , O, , 33. Photo emission is observed for three different metals A,, B and C one by one. Ek versus v graph is plotted for, each metal. Which one of the following graph shows, the phenomenon correctly?, EK, , EK, A, , A, B, , B, C, , (a), , C, , (b), , 27. A charged oil drop falls with terminal velocity vo in the, absence of electric field. An electric field E keeps in, v, v, stationary. The drop acquires additional charge q and, O, O, starts moving upwards with velocity vo. The initial, EK, EK, charge on the drop was, A BC, A B C, (a) 4q, (b) 2q, (c) q, (d) q/2, 28. Let K1 be the maximum kinetic energy of, (c), (d), photoelectrons emitted by light of wavelength 1 and K2, corresponding to wavelength 2. If 1 = 22 then, v, v, (a) 2K1 = K2, (b) K1 = 2K2, O, O, (c) K1< K2, (d) K1 > 2K2, 29. In photoelectric effect the slope of straight line graph 34. Which one of the following graphs will represent the, between stopping potential Vo, variation of photoelectric current (Ip) with the voltage V, Vo and frequency of, applied to the electrodes of a photo-cell?, incident light v gives, Ip, Ip, (a) charge on electrons, (b) work function of emitter, v, (c) Planck’s constant, (a), (b), (d) ratio of Planck’s constant to charge on electron, V, V, O, 30. Light of two different frequencies whose photons have, O, energies 1 eV and 2.4 eV respectively, successively, Ip, Ip, illuminate a metal of work function 0.5 eV. The ratio of, (c), (d), maximum speeds of the emitted electrons will be, (a) 1:5, (b) 1:4, (c) 1:2, (d) 1:1, 31. Monochromatic incident on a metal surface emits, V, V, O, O, electron with kinetic energies from 0 to 2.6 eV. What is, the least energy of the incident photon if the tightly 35. Which one of the following graphs represents correctly, bound electron needs 4.2 eV to remove, the variation of Ekmax with the intensity I of incident, (a) 1.6 eV, (b) between 1.6 eV and 6.8 eV, radiations having a constant frequency, (c) 6.8 eV, (d) more than 6.8 eV, EXmax, EXmax, 32. The work functions for three different metals A, B, C, are WA, WB and WC respectively with WA > WB > WC., The graphs between stopping potential (Vo) and, (a), (b), frequency v for them would look like, O, EX, , \, (a) Vo, , O, , (b) Vo, , C, B, A, , v, , O, , EX, , max, , (c), A, B, C, , Intensity, , max, , (d), O, , v, , O, , Intensity, , Intensity, , O, , Intensity, , 36. The maximum kinetic energy of photoelectrons, emitted from a surface when photons of energy 6eV, fall on it is 4 eV. The stopping potential, in volt, is, (a) 2, , (b) 4, , (c) 6, , (d) 1

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Atomic structure, , Single choice questions, 1. In Rutherford’s experiment the number of alpha particle, scattered through an angle of 90° is 28 per minute. Then, the number of particles scattered through an angle of, 60° per minute by the same nucleus is, (a) 28 per minute, (b) 112 per minute, (c) 12.5 per minute, (d) 7 per minute, 2. Consider the spectral line resulting from the transition n, = 2  n = 1, in the atoms and ions given below, the, shortest wavelength is produced by, (a) hydrogen atom, (b) deuterium atom, (c) singly ionized helium (d) doubly ionized lithium, 3. The radius of the shortest orbit in a oneelectron system, is 18 pm. It may be, (a) Hydrogen (b) deuterium (c) He+, (d) Li++, 4. As the quantum number increases, the difference of, energy between consecutive energy levels:, (a) remain the same (b) increases (c) decreases, (d) sometimes increases and sometimes decreases, 5. According to Bohr’s theory of hydrogen atom, the, angular momentum of an electron of in any orbit of, hydrogen atom is, (a) directly proportional to the radius of the orbit, (b) inversely proportional to the radius of the orbit, (c) directly proportional to the square of the radius, of the orbit, (d) directly proportional to the square root of the, radius of the orbit, 6. In the Bohr model of the atom, an electron can revolve, around the atomic nucleus in a stable orbit without, emitting energy in its orbit. The orbit, (a) is a perfect circle, (b) is a circle of very large radius, (c) contains a whole number of de Broglie waves, (d) contains an odd number of de Broglie waves, 7. The energy of an atom (or ion) in its ground state is, 54.4 eV. It may be, (a) Hydrogen (b) deuterium (c) He+, (d) Li++, 8. As one considers, a, orbits with higher v, d, values of n in a, b, hydrogen atom, the, c, n, , 9., , 10., , 11., , 12., , 13., , 14., , electric potential energy of the atom, (a) Decreases, (b) increases, (c) Remains the same, (d) does not increase, Which of the following curves may represent the speed, of the electron in a hydrogen atom as a function of the, principal quantum number n?, Which of the following parameters are the same for all, hydrogen like atoms and ions in their ground states?, (a) radius of the orbit, (b) speed of the electron, (c) energy of the atom, (d) Orbital angular momentum of the electron, The difference in angular momentum associated with, the electron in the two successive orbits of hydrogen, atom is, (a) h/, (b) h/2, (c) h/2, (d) (n-1) (h/2), Energy level diagram of hydrogen atom is shown in the, adjoining figure along with some transitions marked A,, B, C, D and E. Transitions A, B and C respectively, represent:, (a) ionization potential of hydrogen, third member of, Balmer, n=, 0 eV, series, second n = 6,  0.36 eV, member, of n = 5,  0.54 eV, Paschan series n = 4, D,  0.85 eV, (b) ionization n = 3, C, potential, of, hydrogen,,  0.51 eV, B, second member n = 2,  3.39 eV, of Balmer, series,, third, E, A, member, of n = 1,  13.58 eV, Paschan series, (c) Series limit of Lyman series, third member of, Balmer series, second member of Paschan series, (d) Series limit of Lyman series, second member of, Balmer series and third member of Paschan series, Of the following transitions in hydrogen atom, the one, which gives an absorption line of highest frequency is, (a) n = 1 to n = 2, (b) n = 3 to n = 8, (c) n = 2 to n = 1, (d) n = 8 to n = 3, The total energy of the electron in the hydrogen atom in, the ground state is 13.6 eV. The kinetic energy of this, electron is

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(a) 13.6 eV, (b) 0 (c) 13.6 eV, (d) 6.8 eV, 15. In Bohr’s model of the hydrogen atom the ratio between, the period of revolution of an electron in the orbit of n, =1 to the period of revolution of the electron in the orbit, n = 2 is, (a) 1:2, (b) 2:1, (c) 1:4, (d) 1:8, 16. In which of the following transitions will the, wavelength be minimum?, (a) n = 5 to n = 4, (b) n = 4 to n = 3, (c) n = 3 to n = 2, (d) n = 2 to n = 1, 17. In which of the following systems will the radius of the, first orbit (n = 1) be minimum?, (a) hydrogen atom, (b) deuterium atom, (c) singly ionized helium (d)doubly ionized lithium, 18. In which of the following systems will the wavelength, corresponding to n = 2 to n = 1 be minimum?, (a) hydrogen atom, (b) deuterium atom, (c) singly ionized helium (d) doubly ionized lithium, 19. Paschan series, Brackett series and Pfund series of the, hydrogen spectrum lie, (a) partly in ultraviolet and partly in infrared region, (b) partly in visible and partly in infrared regions, (c) wholly in infrared regions, (d) partly in visible and partly in ultra violet regions, 20. The first excitation potential of a given atom is 10.2, volt. Then ionization potential must be, (a) 20.4 volt (b) 13.6 volt (c) 30.6 volt (d) 40.8 volt, 21. If the series limit wavelength of the Lyman series for, the hydrogen atom is 912 Å, then the series limit, wavelength for the Balmer series of the hydrogen atom, is, (a) 912 Å (b) 912 x 2Å (c) 912 x 4 Å (d) 912/2) Å, 22. Three photons coming from excited atomic-hydrogen, sample are picked up. Their energies are 12.1 eV, 10.2, eV and 1.9 eV. These photons must come from, (a) a single atom (b) two atoms (c) three atoms, (d) Either two atoms or three atoms, 23. Consider the spectral line resulting from the, transition n = 2  n = 1 in the atoms and ions given, below. The shortest wavelength is produced by, (a) Hydrogen atom, (b) deuterium atom, (c) Single ionized Helium (d) Doubly ionized Lithium, 24. As per Bohr model, the minimum energy (in eV), required to remove an electron from the ground state, of doubly ionized Li atom (Z-3) is, (a) 1.51, (b) 13.6, (c) 40.8, (d) 122.4, 25. The electron in a hydrogen atom makes a transition, from an excited state to the ground state. Which of the, following statements is true?, (a) Its kinetic energy increases and its potential and, total energy decreases, (b) Its kinetic energy decreases, potential energy, increases and its total energy remains the same, (c) Its kinetic and total energy decreases and its, potential energy increases, (d) Its kinetic, potential and total energy decreases, 26. If 13.6 eV energy is required to ionize the hydrogen, atom, then the energy required to remove an electron, from n = 2 is, (a) 10.2 eV (b) 0 eV, (c) 3.4 eV, (d) 6.8 eV., 27. If the binding energy of the electron in a hydrogen, , atom is 13.6 eV, the energy required to remove the, electron from the first excited state of Li++ is, (a) 30.6 eV (b) 13.6 eV (c) 3.4 eV (d) 122.4 eV, 28. The diagram shows the energy levels for an electron, in a certain atom., n=4, Which transition, n=3, shown represents, the emission of a, n=2, photon with the, most, energy, І, , ІІ, , ІІІ, , ІV, , n=1, , (a) IV, (b), III, (c) II, (d) I, 29. The angular speed of the electron is the nth orbit, (a) directly proportional to n, (b) inversely proportional to n, (c) inversely proportional to n², (d) inversely proportional to n3, 30. Energy levels A, B, C of a, C, certain atom correspond to, 1, increasing values of energy i.e., B, EA < EB < EC. If 1, 2, 3 are the, wavelengths, of, radiations, 2, 3, corresponding to the transitions, A, C to B, B to A and C to A, respectively, which of the following statements is, correct?, (a) 3 = 1 + 2, (b) 3 = (12)/(1+2), (c) 1 + 2 + 3 = 0, (d) 3² = 1² + 2², 31. Magnetic field at the centre (at nucleus) of the hydrogen, like atoms (atomic number = z) due to the motion of, electron in the nth orbit is proportional to, n4, n3, z2, z3, (a) 5, (b), (c) 3, (d) 5, z, z, n, n, 32. Magnetic moment due to the motion of the electron in, nth energy state of hydrogen atom is proportional to, (a) n, (b) no, (c) n5, (d) n3, 33. Suppose, the electron in a hydrogen atom makes, transition from n = 3 to n = 2 in 108 s. The order of the, torque acting on the electron in this period, using the, relation between torque and angular momentum as, discussed in the chapter on rotational mechanics is, (a) 1034 Nm, (b) 1024 Nm, 42, (c) 10 Nm, (d) 108 Nm, 34. The ratio between total acceleration of the electron in, singly ionised helium atom and hydrogen atom (both in, ground state) is, (a) 1, (b) 8, (c) 4, (d) 16, 35. The shortest wavelength of the Brackett series of a, hydrogen like atom (atomic number = z) is the same as, the shortest wavelengths of the Balmer series of, hydrogen atom. The value of z is, (a) 2, (b) 3, (c) 4, (d) 6, 36. A hydrogen atom is in an excited state of principle, quantum number n. It emits a photon of wavelengths , when returns to the ground state. The value of n is

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(a), , R (R  1), , (b), , (R  1), R, , R, (d) (R  1), (R  1), [R = Rydberg constant], 37. A neutron moving with a speed v makes a head on, collision with a hydrogen atom in ground state kept at, rest. The minimum kinetic energy of neutron for which, inelastic collision will take place is (assume that mass, of proton is nearly equal to the mass of neutron), (a) 10.2 eV (b) 20.4 eV (c) 12.1 eV (d) 16.8 eV, 38. In a hydrogen atoms, the electron is in nth excited state., It comes down to first excited state by emitting ten, different wavelengths. The value of n is, (a) 6(NO. OF ORBIT), (b) 7, (c) 8, (d) 5THE EXITED, 39. Angular momentum (L) and radius (r) of a hydrogen, atom are related as, (a) Lr = constant, (b) Lr² = constant, (c) Lr4 = constant, (d) none of these, 40. The angular momentum of an electron in an orbit is, quantized because it is a necessary condition for the, compatibility with, (a) the wave nature of electron, (b) particle nature of electron, (c) Paulli’s exclusion behaviour, (d) none of these, 41. The maximum angular speed of the electron of a, hydrogen atom in a stationary orbit is, (a) 6.2 x 105 rad/s, (b) 4.1 x 1016 rad/s, 10, (c) 2.4 x 10 rad/s, (d) 9.2 x 106 rad/s, 42. In a hydrogen and hydrogen like atoms the ratio of, difference of energies E4n2n and E2n  En varies with, atomic number z and principle number n as, z, z², z4, (a) 2, (b) 4, (c), (d) none, n, n, n, 43. The ratio of the maximum wavelength of the Lyman, series in hydrogen spectrum to the maximum, wavelengths in the Paschen series is, 3, 6, 52, 7, (a), (b), (c), (d), 15, 105, 7, 108, 44. According to Bohr’s theory of hydrogen atom, the, product of the binding energy of the electron in the nth, orbit in and its radius in the nth orbit, (a) is proportional to n2, (b) is inversely proportional to n3, (c) has a constant value 10.2 eV-Å, (d) has a constant value 7.2 eV-Å, 45. When an electron in the hydrogen atom in ground state, absorbs a photon of energy 12.1 eV, its angular, momentum, , (c), , (a) decreases by 2.11x1034 J-s, (b) decreases by 1.055x1034 J-s, (c) increases by 2.11x1034 J-s, (d) increases by 1.055x1034 J-s, 46. The binding energy of an electron in the ground state of, He is equal to 24.6 eV. The energy required to remove, both the electrons is, (a) 24.6 eV (b) 49.2 eV, (c) 79 eV (d)38.2 eV, 47. The de-Broglie wavelength of electron in ground state, of an hydrogen atom is, (a) 1.06 Å (b) 1.52Å, (c) 0.53Å (d) 3.33Å, 48. Imagine an atom made up of proton and a hypothetical, particle of double the mass of the electron but having, the same charge as the electron. Apply the Bohr atom, model and consider all possible transitions of this, hypothetical particle to the first excited level. The, longest wavelength photon that will be emitted has, wavelength λ (given in terms of the Rydberg constant R, for the hydrogen atom) equal to Level 1, (a)9/5R, (b)36/5R, (c)18/5R, (d)4/R, 49. The transition from the state n = 4 to n =3 in a hydrogen, like atom results in ultraviolet radiation. Infrared, radiation will be obtained in the transition:, (a) 2→1, (b) 3→2, (c) 4→2, (d) 5→4, 50. The transition from the state n = 4 to n = 3 in a, hydrogen like atom results in ultraviolet radiation., Infrared radiation will be obtained in the transition, from:, (a) 3 → 2, (b) 4 → 2 (c) 5 → 4 (d) 2 → 1, 51. The largest wavelength in the ultraviolet region of the, hydrogen spectrum is 122 nm. The smallest wavelength, in the infrared region of the hydrogen spectrum (to the, nearest integer) is, (a) 802 nm (b) 823 nm (c) 1882 nm (d) 1648 nm, 52. Suppose an electron is attracted towards the origin, by a force, , k, ‘k’ is a constant ‘r’ is the distance of, r, , the electron from the origin. By applying Bohr, model to this system, the radius of the nth orbital of, the electron is found to be ‘rn’ and the kinetic energy, of the electron to be ‘Tn’. Then which of the, following is true?, (a) Tn , , 1, , rn  n 2, 2, n, , (b) Tn independent of n, rn  n, (c) Tn , , 1, , rn  n, n, , (d) Tn , , 1, , rn  n 2, n

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Nuclear Physics, , 1., , 2., , 3., , 4., , 5., , 6., , The mass number of a nucleus is, (a) always less than its atomic number, (b) always more than its atomic number, (c) equal to its atomic number, (d) sometimes more than and sometimes equal to its, atomic number., The graph of ln (R/Ro) versus ln A(R = radius of a, nucleus and A = its mass number) is, (a) a straight line, (b) a parabola, (c) an ellipse, (d) none of them, Let Fpp, Fpn and Fnn denote the magnitudes of the, nuclear force by a proton on a proton, by a proton on a, neutron and by a neutron on a neutron respectively., When the separation is 1 fm,, (a) Fpp > Fpn = Fnn, (b) Fpp = Fpn = Fnn, (c) Fpp > Fpn > Fnn, (d) Fpp < Fpn = Fnn, Let Fpp, Fpn and Fnn denote the magnitudes of the net, force by a proton on a proton, by a proton on a neutron, and by a neutron on a neutron respectively. Neglect, gravitational force. When the separation is 1 fm,, (a) Fpp > Fpn = Fnn, (b) Fpp = Fpn = Fnn, (c) Fpp > Fpn > Fnn, (d) Fpp < Fpn = Fnn, Two protons are kept at a separation of 10 nm. Let Fn, and Fe be the nuclear force and the electromagnetic, force between them, (a) Fe = Fn, (b) Fe >> Fn, (c) Fe << Fn, (d) Fe and Fn differ only slightly., Which of the following is a wrong description, of binding energy of a nucleus?, (a) It is the energy required to break a nucleus into its, constituent nucleons., , (b) It is the energy made available when free nucleons, combine to form a nucleus, (c) It is the sum of the rest mass energies of its, nucleons minus the rest mass energy of the, nucleus, (d) It is the sum of the kinetic energy of all the, nucleons in the nucleus., 7. As the mass number A increases, the binding energy, per nucleon in a nucleus, (a) increases, (b) decreases, (c) remains the same, (d) varies in a way that depends on the actual value of, A., 8. Four physical quantities are listed in column I. Their, values are listed in Column II in a random order :, Column II, Column I, (a) Thermal energy of air (e) 0.002 eV, molecules, at, room, temperature, (b) Binding energy per nucleon (f) 2 eV, of heavy nuclei, (c) X-ray photon energy, (g) 1 keV, (d) Photon energy of visible light (h) 7 MeV, The correct matching of column I and II is given by :, (a) a  e, b  h, c  g, d  f, (b) a  e, b  g, c  f, d  h, (c) a  f, b  e, c  g, d  h, (d) a  f, b  h, c  e, d  g, 9. During a nuclear fusion reaction:, (a) a heavy nucleus breaks into fragments by itself

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22.Assuming heat about 20 MeV of energy is released per, fusion reaction, 2, 3, 1, 4, then the mass of 1H2, 1H + 1H  0n + 2He ,, consumed per day in a fusion reactor of power 1, Megawatt will approximately be, (a) 0.001 gm (b) 0.1 gm (c) 10 gm (d) 1000 gm, 23. When a radioactive isotope 88Ra228 decays in series by, the emission of three -particles and a  particle the, isotope finally formed is, (a) 84X220 (b) 86X222 (c) 83X216, (d) 83X215, 24..Assuming that about 200 MeV of energy is released, per fission of 92U235 nuclei, then the mass of U235, consumed per day in a fission reactor of power 1, Megawatt will approximately be, (a) 102 gm (b) 1 gm (c) 100 gm (d) 10000 gm, 25.If mass of U235 = 235.12142 amu, mass of, U236 =, 236.12305 amu and mass of neutron = 1.008665 amu, then the energy required to remove one neutron from, the nucleus U236 is nearly about, (a) 75 MeV (b) 6.5 MeV (c) 1 eV (d) zero, 26. Beta rays emitted by a radioactive material are, (a) electromagnetic radiations, (b) the electrons orbiting around the nucleus, (c) charged particles emitted by the nucleus, (d) neutral particles, 27. The equation, , 1, 4, 4 H   He 2  2e  26MeVrepresents, 1, 2, , (a)  -decay (b) γ-decay (c) fusion (d) fission, 28. Fast neutrons can easily be slowed down by, (a) the use of lead shielding, (b) passing them through water, (c) elastic collisions with heavy nuclei, (d) applying a strong electric field, 29. Masses of two isobars 29Cu64 and 30Zn64 are 63.9298, u and 63.9292 u respectively. It can be concluded, from these data that, (a) both the isobars are stable., (b) Zn64 is radioactive, decaying to Zn64 through  decay., (c) Cu64 is radioactive, decaying to Zn64 through γ decay., (d) Cu64 is radioactive, decaying to Zn64 through , -decay., 30. Order of, magnitude of, Y, 8.5, X, density of, 8.0, W, 7.5, uranium nucleus, is (mp = 1.67 ×, 10-27 kg) :, 5.0, Z, (a) 1020 kgm3 (b), 17, 3, 10 kg/m (c), 1014 kg/m3 (d), 1011 kg/m3, 31. Binding, energy per, 30 60, 90, 120, mass number of nuclei, nucleon vs., mass number, Binding energy per, nucleon in MeV, , (b) a light nucleus bombarded by thermal neutrons, breaks up, (c) a heavy nucleus bombarded by thermal neutrons, breaks up, (d) two light nuclei combine to give a heavier nucleus, and possibly other products., 10. Particles which can be added to nucleus of an atom, without changing its chemical properties are, (a) neutrons, (b) electrons, (c) protons, (d) -particles, 11. The binding energies of the atoms of elements A and, B are Ea and Eb respectively. Three atoms of the, element B fuse to give one atom of element A. This, fusion process is accompanied by release of energy e., Then Ea, Eb and e are related to each other as, (a) Ea + e = 3 Eb, (b) Ea = 3 Eb, (c) Ea  e = 3 Eb, (d) Ea + 3 Eb + e = 0, 12. The binding energy per nucleon of a nucleus is E. The, energy required to remove one proton from such a, nucleus is, (a) E, (b) E/2, (c) > E, (d) < E, 13. The nuclei 6C13 and 7N14 can be described as, (a) isotones, (b) isobars, (c) isotopes of carbon, (d) isotopes of nitrogen, 14. In nuclear fission 0.1% mass is converted into energy., The energy released by the fission of 1 kg mass is, (a) 2.5x105 kWH, (b) 2.5x107 kWH, (c) 2.5x109 kWH, (d) 2.5x107 kWH, 15. If the nuclei of masses x and y fused together to form a, nucleus of mass m and some energy is released, then, (a) x + y = m, (b) s + y < m, (c) x + y > m, (d) x  y = m, 16. The ratio of the radii of the nuclei 13Al27 and 52Te125 is, approximately:, (a) 6 : 10, (b) 13 : 52, (c) 40 : 177, (d) 14 : 73, 17. The number of neutrons in a chain reaction increase in, (a) arithmetic progression, (b) geometric progression, (c) harmonic progression, (d) none of the above, 18. The binding energy per nucleon of 16O is 7.97 MeV, and that of 17O is 7.75 MeV. The energy in MeV, required to remove a neutron from 17O is, (a) 3.52, (b) 3.64, (c) 4.23, (d) 7.86, 19.If mp = 1.00758 amu, mn = 1.00893 amu, me = 0.00055, amu and mass of 3Li7 atom = 7.02780 amu, then the, binding energy of 3Li7 nucleus is, (a) 0.02769 MeV, (b) 30.76 MeV, (c) 7.93 MeV, (d) 0.02769 Joule, 20.In the above problem 108, the binding energy per, nucleon of 3Li7 nucleus is nearly, (a) 0.02769 MeV, (b) 30.76 MeV, (c) 4.39 MeV, (d) 0.02769 Joule, 21.In the nuclear reaction 1H2 + 1H2  0n1 + 2H3. If the, binding energy of deuteron is 2.23 MeV and the Qvalue of the reaction is 3.27 MeV, then the binding, energy of 2He3 is, (a) 1.19 MeV, (b) 7.73 MeV, (c) 4.46 MeV, (d) 3.27 MeV

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(a) Y  2 Z, (b) W  X + Z, (c) W  2 Y, (d) X  Y + Z, 32. The electron emitted in beta radiation originates from, (a) Inner orbits of atoms, (b) Free electrons existing in nuclei, (c) Decay of a neutron in a nucleus, (d) Photon escaping from the nucleus, 33. For uranium nucleus how does its mass vary with, volume, (a) m α V (b) m α 1/V (c) m α √V (d) m α V2, 34. If a star can convert all the He nuclei completely into, oxygen nuclei. The energy released per oxygen nuclei, is: [Mass of He nucleus is 4.0026 amu and mass of, oxygen nucleus is 15.9994 amu], (a) 7.6 MeV, (b) 56.12 MeV, (c) 10.24 MeV, (d) 23.9 MeV, 36. When U238 nucleus originally at rest, decays by, emitting an alpha particle having a speed u, the recoil, speed of the residual nucleus is, (a), , 4u, 238, , (b) -, , 4u, 234, , (c), , 4u, 234, , (d)-, , 4u, 238, , 37. A nucleus with Z = 92 emits the following in a, sequence; α, β-,β-, α, α, α, α, α, β-, β-, α, β+, β+, α. The, Z of the resulting nucleus is, (a) 76, (b) 78, (c) 82, (d) 74, 38. Which of the following cannot be emitted by, radioactive substance during their decay?, (a) Protons (b) neutrinos (c) Helium nuclei (d) electrons, 39. In the nuclear fusion reaction 21H + 31H → 42He + n, given that the repulsive potential energy between the, two nuclei is ~ 7.7 × 10-14 J, the temperature at which, the gases must be heated to initiate the reaction is, nearly[Boltzmann’s Constant k = 1.38 × 10-23J/K], (a) 10 7 K (b) 10 5 K (c) 10 3 K, (b) 10 9 K, 40. The binding energy per nucleon of deuteron (12 H), and helium nucleus ( 24 He) is 1.1 MeV and 7 MeV, respectively. If two deuteron nuclei react to form a, single helium nucleus, then the energy released is, (a) 23.6 MeV, (b) 26.9 MeV, (c) 13.9 MeV, (d) 19.2 MeV, 41. If radius of the 2713 AI nucleus is estimated to be 3.6, fermi then the radius of 12552 Te nucleus be nearly, (a) 8 fermi (b) 6 fermi (c) 5 fermi (d) 4 fermi, 42. If the binding energy per nucleon in 37 Li and, 4, 2, , He nuclei are 5.60 MeV and 7.06 MeV respectively,, then in the reaction, p + 37 Li → 2 24 He, energy of proton must be, (a) 28.24 MeV, (b) 17.28 MeV, (c) 1.46 MeV, (d) 39.2 MeV, 43. If M0 is the mass of an oxygen isotope 8O17 , Mp, and MN are the masses of a proton and a neutron, respectively, the nuclear binding energy of the, isotope is, (a) (M0 – 17 MN )C2, (b) (M0 – 8 Mp) C2, 2, (c) (8Mp + 9MN - MO) C, (d) MOC2, , 44. In gamma ray emission from a nucleus, (a) Only the proton number changes, (b) both the neutron number and the proton, number change, (c) there is no change in the proton number and, the neutron number., (d) only the neutron number changes, 45. The given plot of binding energy per nucleon, Eb, against the nuclear mass M; A, B, C, D, E, F, correspond to different nuclei. Consider four, reactions:, , Eb, , B, , C, , D, , A, , E, F, , M, (i) A + B → C + ε, (ii) C → A + B + ε, (iii) D + E → F +ε and, (iv) F → D + E + ε, where ε is the energy released? In which, reactions is ε positive?, (a) (i) and (iii), (b) (ii) and (iv), (c) (i) and (iii), (d) (i) and (iv), 46. A star initially has 1040 deuterons. It produces energy, via the processes:, 2, 2, 3, 2, 3, 4, 1H + 1H  1H + p, 1H + 1H  2He + n, If the average power radiated by the star is 1016 W and, masses of nuclei are as follows :, M (1H2) = 2.014 a.m.u.,, M (P) = 1.007 a.m.u.,, M (n) = 1.008 a.m.u., M (He4) = 4.001 a.m.u.,, the deutron supply of the star is exhausted in a time of, the order of, (a) 106 sec (b) 108 sec (c) 1012 sec (d) 1016 sec, 47.Binding energy per nucleon vs. mass number curve for, nuclei is, Y, 8.5, X, shown in, 8.0, W, 7.5, the figure., W, X, Y, and Z are, 5.0, Z, four nuclei, indicated, on the, curve. The, process that, would, 30 60, 90, 120, mass number of nuclei, release, energy is, (a) Y  2 Z, (b) W  X + Z, (c) W  2 Y, (d) X  Y + Z, 48. The binding energies of nuclei X and Y are E1 and E2, respectively. Two atoms of X fuse to give one atom of, Y and an energy Q is released. Then, (a) Q = 2E1  E2, (b) Q = E2  2E1, (c) Q < 2E1  E2, (d) Q > E2  2E1, 49. Binding energy per nucleon of 1H2 and 2He4 are 1.1 eV, and 7.0 MeV respectively. Energy released in the, process 1H2 + 1H2 = 2He4 is, (a) 20.8 MeV, (b) 16.6 MeV, (c) 25.2 MeV, (d) 23.6 MeV, Binding energy per, nucleon in MeV, , curve for nuclei is shown in the figure. W, X, Y and Z, are four nuclei indicated on the curve. The process that, would release energy is

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50. If 92U238 changes to 85At210 by a series of  and , decays, the number of  and  decays undergone is, (a) 7 and 5, (b) 7 and 7, (c) 5 and 7, (d) 7 and 9, Radioactivity, , 1. The same radioactive nucleus may emits, (a) all the three ,  and  radiations simultaneously, (b) all the three ,  and  one after another, (c) only  and  simultaneously, (d) only one  or  and  at a time, 2. The radioactive decay rate of a radioactive element is, found to be 103 disintegrations /sec at a certain time. If, the half-life of the element is 1 second, the decay rate, after one second is … and after 3 seconds is …, (a) 500, 125 (b) 125, 500 (c) 103, 103 (d) 100, 10, 3. If only one atom of a radioactive element is left, then, this atom disintegrations after, (a) half value period, (b) mean value period, (c) a time which cannot be specified, (d) infinite time, 4. Half-life period of lead is, (a) zero (b) infinite (c) 1590 days (d) 1590 years, 5. Which of the following processes is not related to, radioactive decay?, (a) positron emission, (b) electron capture, (c) nuclear fusion, (d) -decay, 6. N1 atoms of a radioactive element emit N2 beta, particles per second. The decay constant of the, element is (in sec1), N, N, (a) 1, (b) 2 (c) N1 ln(2), (d) N2 ln(2), N2, N1, 7. If 10% of a radioactive material decays in 5 days, then, the amount of the original material left after 20 days is, approximately, (a) 60%, (b) 65%, (c) 70%, (d) 75%, A, A, 0, 8. The equation : ZX  Z+1Y + 1e +v, , 9., , 10., , 11., , 12., , 13., , 14., , represents, (a) -decay (b) -decay (c) fusion (d) Fission, The counting rate observed from a radioactive source, at t = 0 second was 1600 counts per second and at t = 8, seconds it was 100 counts per second. The counting, rate observed, as counts per second at t = 6 seconds, will be, (a) 400, (b) 300, (c) 200, (d) 150, B210 has a half-life of 5 days. The time taken for seveneight of a sample of decay is, (a) 3.4 days (b) 10 days (c) 15 days (d) 20 days, In a radioactive decay, neither the atomic, number not the mass number changes. Which of, the following particles is emitted in the decay?, (a) proton (b) neutron (c) electron (d) photon, During a negative beta decay?, (a) an atomic electron is ejected, (b) an electron which is already present within the, nucleus is ejected, (c) a neutron in the nucleus decays emitting an, electron, (d) a proton in the nucleus decays emitting an electron, The radioactive element which is used for finding the, age of fossils is, (a) 6C12, (b) 6C14, (c) radioactive nitrogen, (d)radioactive oxygen, An archaeologist analyses the wood in a prehistoric, structure and finds that the radio of C14 (half-life 5700, years) to ordinary carbon is only one-fourth of that, found in the cells of living plants. The age of the wood, is about:, (a) 5700 years, (b) 2850 years, (c) 11400 years, (d) 22800 years

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15. In the reactions represented by, A, A4,  Z2XA4  Z1XA4, ZX  Z2X, the decays in the sequence are, (a) , ,  (b) , ,  (c) , , , (d) , , , 16. In a nuclear reaction involving a deuteron and 3Li+7,, one finds 3Li8. The other product must be, (a) proton, (b) neutron, (c) gamma ray, (d) nothing is formed, 17. The equation: ZXA  Z1YA + 1e0 + v represents, (a) -decay (b) -decay (c) fusion (d) fission, 18. An element X decays first buy positron emission and, then two -particles are emitted in successive, radioactive decay. If the product nucleus has a mass, number 229 and atomic number 89, the mass number, and atomic number of element X are, (a) 237, 93 (b) 237, 94 (c) 238, 93 (d) 237, 92, 19. The nucleus 6C12 absorbs an energetic neutron and, emits a beta particle (). The resulting nucleus is, (a) 7N14, (b) 5B13, (c) 7N13, (d)6C13, 20. The half life of radioactive Radon is 3.8 days. The, time at the end of which, , 1, th of the radon sample will, 20, , remain undecayed is (given log10 e = 0.4343), (a) 3.8 days (b) 16.5 days (c) 33 days (d) 76 days, 21. The half-life of 215At is 100μs. The time taken for, the radioactivity of a sample of 215At to decay to, 1/16th of its initial value is, (a) 400 μs (b) 6.3 μs, (c) 40 μs (d) 300 μs, 22. A 280 days old radioactive substance shows an activity, of 6000 dps, 140 days latter its activity become 3000, dps, what was its initial activity, (a) 20000 dps, (b) 24000 dps, (c) 12000 dps, (d) 6000 dps, 23. A radioactive sample S1 having an activity 5μ Ci has, twice the number of nuclei as another sample S2 which, has an activity of 10 μCi. The half lives of S1 and S2, can be, (a) 20 years and 5 years , respectively, (b) 20 years and 10 years , respectively, (c) 10 years each, (d) 5 years each, 24. If N0 is the original mass of the substance of half-life, period t1/2 = 5 years, then the amount of substance, left after 15 years is, (a) N0/8, (b) N0/16, (c) N0/2, (d) N0/4, 25. A radioactive sample at any instant has its, disintegration rate 5000 disintegrations per minute., After 5 minutes, the rate is 1250 disintegrations per, minute. Then, the decay constant (per minute) is, (a) 0.4 In 2 (b) 0.2 In 2 (c) 0.1 In 2 (d) 0.8 In 2., 26. Starting with a sample of pure 66Cu , 7/8 of it decays, into Zn in 15 minutes. The corresponding half life is, (a) 15 minutes, (b) 10 minutes, (c) 7, , 1, min utes, 2, , (d) 5 minutes, , 27. The half-life period of a radio-active element X, is same as the mean life time of another radioactive element Y. Initially they have the same, number of atoms. Then, (a) X and Y decay at same rate always, (b) X will decay faster than Y, , (c) Y will decay faster than X, (d) X and Y have same decay rate initially, 28. The decay constant of a radioactive sample is λ. The, half -life and mean-life of the sample are, respectively given by, (a) I/ λ and (In 2) I/ λ, (b) (In 2)/ λ and I/ λ, (c) λ (In 2) and I/ λ, (d) λ /(In 2) and I/ λ, 29. A radioactive substance is being produced at a, constant rate of 200 nuclei/s. The decay constant of the, substance is 1s1. After what time the number of, radioactive nuclei will become 100. Initially there are, no nuclei present, 1, (a) 1 sec, (b), sec (c) ln (2) sec (d) 2 sec, ln(2), 30. There are two radio nuclei A and B. A is an alpha, emitter and B is a beta emitter. Their disintegration, constants are in the ratio of 1:2. What should be the, ratio of number of atoms of A and B at any time t so, that probabilities of getting alpha and beta particles are, same at that instant, (a) 2:1, (b) 1:2, (c) e, (d) e1, 31. Half life of a radioactive substance A is two times the, half life of another radioactive substance B. Initially, the number of nuclei of A and B are NA and NB, respectively. After three half lives of A, number of, nuclei of both are equal. Then the ratio NA/NB is, (a) 1/4, (b) 1/8, (c) 1/3, (d) 1/6, 32. There are two radioactive substances A and B. Decay, constant of B is two times that of A. Initially both have, equal number of nuclei. After n half lives of A rate of, disintegration of both are equal. The value of n is, (a) 1, (b) 2, (c) 4, (d) all of these, 33. A radioactive nucleus A finally transforms into a, stable nucleus B. Then A and B can be, (a) isobars, (b) isotones, (c) isotopes, (d) none of these, , 34. Number of nuclei of a radioactive substance at time, t = 0 are 1000 and 900 at time t = 2s. Then number of, nuclei at time t = 4 s will be, (a) 800, (b) 810, (c) 790, (d) 700, 35. In a sample of a radioactive substance what fraction of, the initial number of nuclei will remain undecayed, after a time t = T/2, where T = half life of radioactive, substance, 1, 1, 1, 1, (a), (b), (c), (d), 4, 2, 2 1, 2 2, 36 The activity of a radioactive substance is R1 at time t1, and R2 at time t2 (> t1). Its decay constant is . Then, (a) R1t1 = R2t2, (b) R2 = R1 e ( t1  t 2 ), R  R2, (c) 1, = constant, (d) R2 = R1 e ( t 2  t1 ), t 2  t1, 37. In the above problem, number of atoms decayed, between time interval t1 and t2 are, ln(2), (R 1  R 2 ), (a), (b) R1 e t1  R2 R1 e t 2, 

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 R  R2 , (d)  1, , , , , 38. The ratio of molecular mass of two radioactive, 3, substance is, and the ratio of their decay constant is, 2, 4, . Then the ratio of their initial activity per mole will, 3, be, (a) 2, (b) 8/9, (c) 4/3, (d) 9/8, 39. A freshly prepared radioactive source of halflife 2 h, emits radiation of intensity which is 64 times the, permissible safe level. The minimum time after which, it would be possible to work safely with this source is, (a) 6 h, (b) 12 h, (c) 24 h, (d) 128 h, 40. A radioactive sample consists of two distinct species, having equal number of atoms initially. The mean life, time of one species is τ and that of the other is 5τ. The, decay products in both cases are stable. A plot is made, of the total number of radioactive nuclei as a function, of time. Which of the following figures best represents, the form of this plot?, , (c) (R1  R2), , N, , (a), , N, , τ, , (b), t, , N, , τ, , t, , τ, , t, , N, , (c), , (d), τ, , t, , 41. At a specific instant emission of radioactive compound, is deflected in a magnetic field. The compound can, emit, (i) electrons (ii) protons, (iii) He2+ (iv) neutrons, The emission at instant can be, (a) i, ii, iii, (b) i, ii, iii, iv, (c) iv, (d) ii, iii, , ........By Praveen Gypta